Vehicles have become popular that use systems such as an ABS (Antilock Brake System) that controls a brake according to a rotation speed for each wheel. In such a vehicle, a magnetic sensor is used to detect the rotation speed for a wheel (for example, see Japanese Pub. Patent App. 2008-268016).
In the magnetic sensor described in Japanese Pub. Patent App. 2008-268016, a plate-shaped magnetoelectric converter and two leads connected to the magnetoelectric converter are arranged in a cylindrical holder with a bottom. The holder is filled with resin when the magnetoelectric converter and the leads are arranged therein.
The magnetoelectric converter is structured so as to be positioned at one end of the holder, converts a magnetic field that permeates a plate surface of the magnetoelectric converter to an electric signal according to the strength of the magnetic field, and outputs the converted electric signal via the two leads.
The magnetic sensor described in Japanese Pub. Patent App. 2008-268016 is used to detect a rotation speed of an annular-shaped magnetic encoder that rotates along with a wheel in which S-polarity magnets and N-polarity magnets are alternatingly aligned in a circumferential direction. It is arranged in the vicinity of the magnetic encoder.
If the magnetic encoder is rotated by the wheel, the strength of the magnetic field in the vicinity of the magnetic sensor described in Japanese Pub. Patent App. 2008-268016, in other words the magnetic field that permeates the magnetoelectric converter, fluctuates. At this time, an electric signal that corresponds to the strength of the magnetic field that permeates the magnetoelectric converter, in other words to the rotation speed of the wheel, is output from the magnetoelectric converter via the two leads, and the rotation speed of the wheel is detected based on the output electric signal.